In a motor vehicle comprising a thermal engine and a rotary electrical machine such as an alternator-starter, a machine of this type comprises in a non-limiting manner:                a rotor comprising an inductor in which an excitation current is conveyed; and        a stator comprising a polyphase winding.        
The alternator-starter operates in motor mode or in generator mode. It is a so-called reversible machine.
In alternator mode, which is also known as generator mode, the machine makes it possible to transform a movement of rotation of the rotor driven by the thermal engine of the vehicle into an electric current induced in the phases of the stator. In this case, a rectifier bridge which is connected to the phases of the stator makes it possible to rectify the induced sinusoidal current into a direct current in order to supply consumers of the vehicle, as well as a battery.
On the other hand, in motor mode, the electrical machine acts as an electric motor which makes it possible to rotate the thermal engine of the vehicle via the rotor shaft. It makes it possible to transform the electrical energy into mechanical energy. In this case, an inverter makes it possible to transfer a direct current obtained from the battery into an alternating current in order to supply the phases of the stator, so as to make the rotor rotate,
Control components are used to determine the operating mode of the rotary electrical machine (motor mode or generator mode) via control signals,
The power components (inverter and rectifier bridge) are in general distributed in one power module per in bridge arm.
Each power module consists of:                an over-moulded conductive tracks part of the MIL (Isolated Moulded Leadframe) type contained in a top of the range plastic housing which can withstand high temperatures. A plurality of electronic switches, conventionally MOSFETs, are welded at a high temperature onto the circuit of conductive tracks, with the electronic switches of a module being, designed to form an inverter/rectifier bridge arm for a phase of the rotary electrical machine;        a substrate of the ceramic type on which there are glued components (known as drivers) which are designed to provide the control of the power switches;        a rear conductive plate, typically made of aluminium (known as a backplate) which makes it possible to form the earth of the inverter/rectifier bridge;        a plastic cover of the PPS, PBT or PA type, which makes it possible to ensure the sealing of the power module;        signal connection pins which are integrated in the housing, and ensure a connection with an interconnection part which permits transit of power signals between the power module and a control module.        
Each power module is tested individually, then fitted on a dissipater of the electrical machine by means of a plurality of screws per power module. Then, for each power module, firstly electrical welds are produced for connection to the phases of the electrical machine and to a power interconnector, for connection to a terminal, known as the terminal B+, for connection to the battery of the vehicle, and secondly laser welds are produced for connection of signal pins to a control module. Then, resin or silicon gel is deposited in order to guarantee protection of the laser welds against aggression from the environment, and to ensure the sealing of the module. Then finally, the electrical machine as a whole is tested.
A disadvantage of this prior art consists in the fact that, during the final testing of the electrical machine as a whole, if any one problem is detected, for example on a power module, the electrical machine as a whole must be scrapped, because the elimination of the welds gives rise to deterioration of the electrical machine.
In this context, the objective of the present. invention is to resolve the disadvantage previously described.